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为了探讨农田防护林带的农业经济效益及其合理的农林用地比例,我们在合阳县选择有代表性的乡,再在每个乡选择典型的农林立体结构样地,进行气候效益观测,并利用在林木影响下的农田近五年的平均粮食产量与无林木影响的空旷地五年平均产量作比较,计算农田防护林带的农业经济效益。一、农田防护林带的气候效应农田防护林带下的小气候不同于单一的农田小气候,它有改善农田小气候,创造出有利于农作物生长发育的生态环境。观测结果列入表1。由上表观测结果可以看出,防护林带对农田小气侯的改善有明显作用,其规律是:(1)降低风速作用明显。平均可降低风速
In order to explore the agricultural economic benefits of farmland shelter belts and their reasonable proportions of agricultural and forestry land use, we selected representative townships in Heyang County, and then selected the typical three-dimensional structure of agriculture and forestry in each township for climate benefit observation. The agricultural economic benefits of farmland shelterbelts were calculated by comparing the average grain yield of the farmland under the influence of trees with the five-year average yield of open land without the impact of trees. First, the climate effect of farmland shelterbelt Microclimate under the farmland shelterbelt is different from a single farmland microclimate, which can improve the microclimate of farmland and create an ecological environment conducive to the growth and development of crops. The observations are listed in Table 1. As can be seen from the above table, the shelterbelt has a significant effect on the improvement of microclimate in farmland. The regularities are as follows: (1) The effect of wind speed reduction is obvious. The average wind speed can be reduced